The subject matter herein relates generally to circuit boards having signal and ground pathways.
Communication systems exist today that utilize pluggable connector assemblies to transmit data. For example, network systems, servers, data centers, and the like may use numerous cable assemblies to interconnect the various devices of the communication system. Cable assemblies may include a pluggable connector that is configured to be inserted into a receptacle assembly of a communication system. The pluggable connector includes signal pathways and ground pathways in which the signal pathways convey data signals and the ground pathways control impedance and reduce crosstalk between the signal conductors. In differential signaling applications, the signal pathways are arranged in signal pairs for carrying the data signals. Each signal pair may be separated from an adjacent signal pair by one or more ground pathways.
The pluggable connectors may be configured to transfer electrical signals in accordance with industry standards. By way of example, known industry standards for pluggable connectors include small-form factor pluggable (SFP), enhanced SFP (SFP+), quad SFP (QSFP), C form-factor pluggable (CFP), and 10 Gigabit SFP, which is often referred to as XFP. Among other things, these standards may require that the pluggable connectors have certain physical configurations or structures.
There has been a general demand to increase the speeds at which data is transmitted through the communication systems. As data rates increase, however, it becomes more challenging to maintain a baseline level of signal quality. For example, electrical energy that flows along the surface of each ground pathway may form a field that propagates between the ground pathways. The ground pathways may couple with each other to support an unwanted electrical propagation mode that is repeatedly reflected and forms a resonating condition (or standing wave). Electrical noise caused by the resonating condition may increase return loss and/or crosstalk and reduce throughput of the interconnect system.
To control resonance between ground pathways and limit the effects of the resulting electrical noise, it has been proposed to electrically common the ground pathways using metal grounding bars, ground planes or grounded housings. The effectiveness and/or cost of implementing these techniques is based on a number of variables, such as the geometries of the signal and ground pathways within the interconnect system. Moreover, these techniques are usually applied to the receptacle assembly that receives the pluggable connector. It may be difficult to implement these and other techniques in pluggable connectors due to the structural requirements for pluggable connectors that are set by the industry standards.
Accordingly, there is a need for interconnect systems that reduce electrical noise caused by resonating conditions in ground pathways.